An input/output connector (I/O connector) generally includes an insulation body and at least one row of contacts arranged in parallel on the insulation body. Each contact includes a solder foot at a first end thereof and a contact portion at an opposite second end thereof. The solder foot of each contact is adapted to be soldered to a solder pad of a circuit board and the contact portion of each contact is adapted to be in electrical contact with a contact pad of a card inserted into the connector.
A conductive via is generally formed on each of a plurality of ground solder pads of the circuit board corresponding to a plurality of ground contacts of the row of contacts; the conductive via is located on a signal flow side of the corresponding ground solder pad away from a tail of the solder foot of the corresponding ground contact. Similarly, a conductive via is generally formed on each of a plurality of ground contact pads of the card corresponding to the ground contacts of the row of contacts; the conductive via is located on a signal flow side of the corresponding ground contact pad away from a tail of the contact portion of the corresponding ground contact. In a connector having such a structure, however, it is difficult to effectively suppress resonance of the connector.